Polymerization of olefins in the presence of nitrogen compounds



Patented Aug. 2, 1949 POLYMERIZATION OF OLEFINS IN THE PRESENCE OF NITROGEN COMPOUNDS Adrianna Johannes van Peski, deceased, late of Amsterdam, Netherlands, by Carolina Catharlna Johanna van Peski, executrix, Bnssnm, Netherlands, assignor to Shell Development Company, San Francisco, Calif., a corporation of Delaware No pmwlllg. Application August 7,1941, Serial No. 767,320. In the Netherlands April 20, 1944 Section 1, Public Law 690, August 8, 1948 Patent expires April 20, 1964 11 Claims. (Cl. 260-68315) This invention relates to the production of olefin polymers, particularly to the manufacture of higher molecular hydrocarbons such as gasoline and lubricating oil from lower oleflns, and provides an especially advantageous method of carrying out such polymerizations in the presence of compounds which form free radicals under the reaction conditions.

It has been suggested that the non-catalytic polymerization of oleflns takes place by a free radical mechanism, and it has been proposed to promote polymerization by the addition of compounds which form free radicals, particularly the metal alkyls such as the lead tetraalkyls and mercury diaikyls. It has now been found that improved results may be obtained by the use in polymerization reactions of an especially advantageous class of compounds, namely, the acidic organic nitrogen compounds which derive their acidic properties solely from the nitrogen-containing group of the molecule. These polymerization promoters consist of two main subgroups of related compounds, 1. e. the nitrohydrocarbons and the imino compounds. Of these, the imino compounds ofler special advantages. The simplest oi imino compounds which may be used are the imines themselves, which include the al- Other related imino compounds which may also be used include the imino amines NE R RHi-N and the imido esters These compounds may all be represented by the formula N-A nix-a where R represents H or hydrocarbon, R. represents H, hydrocarbon,

or 0-H, and A represents H, OH, NH: or

in which R, and R represent H or hydrocarbon. Together with the closely related acidic nitrohydrocarbons, particularly the nitroalkanes and nitrocycloalkanes, these compounds have been found to give especially advantageous results in the polymerization of a wide variety of oiefins. Under the reaction conditions they decompose and liberate free radicals which catalyze the desired olefin polymerization.

Typical examples of oleflns which may be polymerized according to the invention are the alkenes and cycloalkenes such, for instance, as ethylene, propylene, the normal and iso-butylenes, the amylenes, cyclopentene, the methyl cyclopentenes, cyclohexene, the methyl cyclohexenes, and higher oleflns such, for instance, as the oleflns of cracked gasoline or those of still higher boiling point such as the so-called cracked wax olefins obtained by cracking, preferably in the vapor phase, paraflin wax and the like to produce olefins of 8 to about 22 carbon atoms. The olefins may be used as pure or substantially pure individual compounds or as suitable mixtures thereof with or without compounds which do not interfere with the reaction. Fractions of petroleum cracking products wherein the oleflns are present with the corresponding paramns are particularly advantageous starting materials for the process.

The process may be carried out in the liquid or vapor phase. Temperatures between about 100 C. and 400 C. are suitable, preferably temperatures between 200 C. and 300 C. Elevated In all cases about 30 per cent by volume of the polymerization product consisted of products with a boiling point 150 C., mainly consisting of isohexenes and iso-nonenes. the remainder being pressures are especially advantageous in the remade up of higher boiling polymerization prodaction, and it has been found that pressures above ucts. I 100 atmospheres are particularly desirable in Other examples 0! imino compounds which may giving appreciably higher yields of polymerizabe used in the same way are, for instance, acetamtion products under otherwise similar conditions. idine, ethenyl-diphenyl amidine, aldehydephen- The higher pressures of 100 to 1000 atmospheres l0 yl-hydrazone, acetone-phenyl-hydrazone, isonior more are especially advantageous in the protrosoacetone, methylene imine, ethylidene imine, duction of lubricating oils according to the inbenzylidene imine, trimeric methylene methyl vention. The average degree of polymerization imine, ethylidene phenyl imine, benzylidene phedecreases with increased temperature and innyl imine, anhydroi'ormalde-aniline, hydrobenzcreases with increased pressure. By the selection amide, isopropylidene imine, acetophenoneimine, of the proper combination of temperature and isopropyiidene phenyl imine, isophoroneimine, pressure, a wide variety of products may be proformamidine, V benzamidine, phenylbenzamidine, duced. Those of lower molecular weight. for ex- N,N'-diphenyl benzamidine, N,N-diphenyl benzaample, boiling in the gasoline range, are usually midine, benzil dioxime, methyldecyl ketoxime, more unsaturated in character than the higher acetimido ethyl ester. olymerization products, and for the production The production of imidines and acylamidines of gasoline blending agents according to the procwhich are suitable for use as polymerization proess it is usually desirable to hydrogenate the moters according to the invention is described, initial polymer. The products so obtained have for instance, in U. S. Patent 2,196,447. Especially high octane numbers. The higher boiling polyadvantageous methods of producing imines which mers in the lubricating oil range have high vismay also be used are disclosed in copending applicosity indices and a high pour point indicating cations Serial No. 522,376, filed February 14, 1944 a low de ree 0f b 18- S l higher p lymers now Patent No. 2,422,013, and Serial No. 717,322, having, for instance, molecular weights exceedfiled December 19, 1946. As a rule, the preferred ing 10,000 may be obtained. These solid hydroimino compounds are those having hydrocarbon carbons may advantageously be used in the radicals of not more than six carbon atoms. manufacture of molded products. The following E l I] example shows the advantages of the new process. mm? 6 Example About 500 g. of pure propene were heated together with 2 g. of nitro-ethane at different tem- When heating about 250 g. of pure propylene peratures under a pressure of 250 atms. for 1 /2 in an autoclave with a capacity of 1 liter at 300 hours. C. for various periods of time at an initial pressure The results are listed in the following table, of 250 atms., the following results were obtained: as well as the yields of polymerization product. After a reaction period of 1 hr., 3% g. of liquid in case no nitm'ethane was addedpolymerization product k After a reaction period of 1 hrs, 4 g. of liquid G. Polymerization Prodpolymerization product 2 8?" in-53 3c? g ki fgg ggfi ig g 'f After a reaction period oi 2 hrs., 7 g. of liquid Nitmethm" p 00 sofPropene polymerization product After a reaction period 01' 2 /2 hrs, 9 g. of liquid 275 0 17 polymerization product 3 53 53 After a reaction period of 3 hrs. 10% g. of liquid 350 124 232 polymerization product 375 324 369 After a reaction period of 3% hrs., 12 g. of liquid polymerization product Example III The increase in yield from adding various small Six hundred grams of propene, to which 4.5 g. amounts of imino compounds according to the 0f y -propyl-ketazine had been added, invention is shown in the following table in comwere heated to 230 C., the initial pressure being parison with the results obtainable by the use, 250 atms. Forty-two grams of polymerization under the same conditions, of metal alkyls and product were then obtained, 16 Pe c t of wh ch basic nitrogen compounds: consisted of hydrocarbons with a boiling point Number oig. Emotion Grams of Grams of Polymerization Promoters 3 3313? g zgg a g g m tim ti i i fi i zr 0.9 1.5 11 64.8 0.0 1.5 60 44.4 1.0 1.5 63 42' 1.4 1% 64 30.2 1.3 1.5 64 as methyi-n-propylketezine 2.1 1.6 31.7 methyl-t-butyiketazine- 2. 4 l. 5 100 30. 2 dimethylketazine 1.4 2.5 94 27 mesityloxime 1. 4 l. 5 60 24 tetraethyl lead l. 0 l. 6 35 23 benzene diazodimethylamide. 1. 8 l. 5 56 20. 6 tetramethyl lead 0. 9 l. 6 27. 5 2o. 3 di-azo-aminobenzene l. 0 2. 5 30 14. 4 di-azo-amino-p-toluene. 1. 0 3 37 12. 3 azo-toluene 1. 0 2. 6 18 7. 2

below 150 C. Forty per cent of the product was made up of lubricating oil with a boiling point above 200 C. mm.).

When no methyl-n-propylketazine was added. no polymerization took place.

Example IV Example V When heating 140 g. of pure ethene, to which 0.1 g. of methyl-n-propylketazine had previously been added, at a temperature of 240 C. and a pressure of about 950 atms. for three hours, 100 g. of polymerization product were obtained with an average molecular weight exceeding 10,000. Without the addition of methyl-n-propylketazine, under otherwise similar conditions, only 5 g. of polymerization product with corresponding properties were obtained.

Erample VI Ethylene was polymerized in the same manner at a temperature of 260 C. and initial pressure of 250 atms., using methyl normal propyl ketazine as the promoter, and it was found that for the per gram mole of polymer used 1310 gram moles of olefin were polymerized, while at a temperature 320C. and an initial pressure of 250 atms. is shown by the following results:

Concentration oi G. moles of Propylene Methyl-n-propylketazine Polymerized per R. mole of g. molesX 10- per liter Methyl-n-propylketazine As a rule, the polymerization obtained with a given amount of imino compound or nitrohydrocarbon decreases with the concentration of these promoters in the hydrocarbon mixture being used. However, too low a concentration of promoter will unduly reduce plant capacityhence, concentrations of about 0.0005 to 0.05, preferably 0.002 to 0.01, gram moles per liter are used.

No effect on the reaction was produced by the wall of the reaction vessel or the presence of slight impurities in the feed. Thus, increasing the wall surface six times by filling the reactor with fragments of glass produced no substantial influence on the reaction. Small amounts of impurities such as water, sulfur and lubricating oil in the feed also had no effect. However, excessive dilution of the olefin with paraflln reduces the yield. Olefin mixtures polymerize to about the same extent that they would independently so that it is possible to interpolate from the results for the pure olefins and obtain the yields for any given mixture.

The quality of the products appears to be independent of the particular imino compound or nitrohydrocarbon used in the reaction. Typical lubricating oils obtained by polymerizing ethylene at 300 C. and 200 atms. have the following properties:

of 300 C. 1460 gram moles of ethylene were polymerized per gram mole of methyl normal propyl ketazine used.

Example VII Propylene was polymerized in a series of batches using different nitro compounds as the promoters. In all cases a polymerization temperature of 300 C. was used and a pressure of 250 atms. was applied at the start. The reaction time was 1.5 to 3.5 hours.

Example VIII The eflect of concentration of methyl-n-propylketazine in the po merization of propylene at It will be seen from the foregoing that the invention ofiers many advantages over prior methods of polymerizing olefins. It will be understood, however, that it is not limited to the details disclosed by way of example since many variations may be made in the process. Thus, for example, while polymerization in the presence of the specified nitrohydrocarbons and imino compounds as the sole polymerization promoters has been emphasized, these promoters can also be used in conjunction with other polymerization promoters or with catalysts such, for instance, as solid phosphoric acid catalysts and the like. In such methods of operation the polymerization using the imino compounds and nitrohydrocarbons can be carried out either subsequent or prior to the phosphoric acid-catalyzed polymerization or simultaneously therewith. Batch or intermittent polymerization may be used as well as continuous reaction.

The invention claimed is:

l. A process of polymerizing an olefin which comprises heating said olefin to a temperature of at least C. in the presence of an acidic organic nitrogen compound which derives its acidic properties solely from the nitrogen-containing group of the molecule and which decomposes under the reaction conditions.

2. A process of polymerizing an olefin which comprises heating said olefin to a temperature between 100 C. and 400 C. in the presence of an acidic organic nitrogen compound having a rivalent nitrogen atom linked by a double bond to a single carbon atom of a divalent organic radical, which organic nitrogen compound decomposes under the reaction conditions.

3. A process of producing a polymer which comprises heating a, normally gaseous alkene at a temperature of 100 C. to 400 C. and a pressure in excess of 100 atmospheres in the presence of an acidic organic nitrogen compound having a trivalent nitrogen atom linked by a double bond to a single carbon atom of a divalent hydrocarbonradical, which organic nitrogen compound decomposes under the reaction conditions.

4. A process of polymerizing an olefin which comprises heating said olefin to a temperature above 100 C. under a pressure of at least 100 atmospheres in the presence of an organic nitrogen compound which decomposes under the reaction conditions and which contains a trivalent nitrogen atom directly linked by a double bond to an alkylidene radical.

5. A process of producing polymers which comprises heating an alkene at a temperature above 100 C. and a. pressure in excess of 100 atmospheres in the presence of an organic nitrogen compound having a -C=N group in the molecule, which compound decomposes under the reaction conditions.

6. A process of producing a polymer which comprises heating an alkene at a temperature of 100 C. to 400 C. under a pressure of at least 100 atmospheres in the presence of a nitrohydrocarbon which decomposes under the reaction conditions.

7. A process of producing polymers which comprises heating a normally gaseous olefin at a temperature above 100 C. in the presence of an 8 aliphatic nitrohydrocarbon or not more than 6 carbon atoms per molecule.

8. A process of polymerizing an olefin which comprises heating said olefin to a'temperature between C. and 400 C. under a pressure of at least 100 atmospheres in the presence of a hydrocarbon 'azine which decomposes under the reaction conditions.

9. A process of producing polymers which comprises heating a normally gaseous olefin at a temperature above 100 C. in the presence of an acidic ketazine which decomposes under the reaction conditions.

10. A process of producing a polymer which comprises heating an alkene at a temperature of 100 C. to 400 C. in the ,presence of an aliphatic ketazine having not more than 6 carbon atoms per molcuie.

11. A process of producing polymers which comprises heating a normally gaseous olefin at a temperature between 200 C. and 300 C. in the presence of a methylpropylketazine.

CAROLINA CATHARINA JOHANNA VAN PESKI, Executriz of the Estate of Adrianna Johannes van Peski, Deceased.

REFERENCES CITED The following references are of record in the tile of this patent:

UNITED STATES PATENTS Number Name Date 2,156,718 Bent et a1. May 2, 1939 2,237,459 Thompson Apr. 8, 1941 2,377,411 Frey June 5, 1945 2,398,926 Dorough Apr, 23, 1946 2,405,950 Hani'ord Aug. 20, 1946 2,439,528 Roedel Apr. 13, 1948 2,462,678 Roedel Feb. 22, 1949 2,462,680 Sargent Feb. 22, 1949 

